If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

You're on the right track, except +/-1.5% = 0.015 x 4" = 0.06" wc. I suggest you look at instruments with a full scale deflection closer to what you are trying to measure. For instance, a Dyer Magnehelic 2000-0 with a full scale of 0.50" wc & and an accuracy of +/-3% FS has an error of .03 x .5 = 0.015". I bought one of these on eBay a while back for $35. Also, Dyer will calibrate their instruments for a fee.

great tip. that would be more accurate. I asked dwyer and they just suggested their 400$ digital high range unit that was not any more accurate. I hope their gauges are better then their customer service.

On their Magnehelic 2000 page i also see one that is 0.25-0-0.25" w.c. and another that is 0.125-0-0.125" w.c.